1. Field of the Invention
The present invention relates to a surface light source which selectively irradiates light beams in two polarized states different from each other, and a liquid crystal display apparatus using the surface light source.
2. Description of the Related Art
A liquid crystal display apparatus includes a liquid crystal display device and a surface light source. The liquid crystal display device has front and rear polarizing plates respectively placed on the front surface facing the observation side of display and the rear surface on the opposite side to the front surface. The surface light source is placed behind the liquid crystal display device and applies illumination light to the screen area of the liquid crystal display device. The liquid crystal display device is driven by a driving unit which sequentially supplies image data to the pixels of the liquid crystal display device for each frame to display a one-frame image. The liquid crystal display device has a screen area where pixels which control the transmission of light are arrayed in the row and column directions. The liquid crystal display device displays an image corresponding to image data by using the pixels.
The liquid crystal display apparatus uses the hold display mode of holding the display of an image corresponding to image data written in a given frame on a frame basis. For this reason, when displaying a moving image such as a television image, this apparatus gives the observer of the display a feeling of blur, i.e., makes observer see an after image of the displayed image of a preceding frame which is superimposed on the displayed image of the next frame.
As a countermeasure against such blurring of the display of a moving image, there has been known a technique of preventing an after image of the displayed image of a preceding frame from remaining on the next frame by performing black display in the period between a frame for displaying an image corresponding to image data and the next frame for displaying a subsequent image.
As display techniques based the above image display and black display, there have been proposed a technique of alternately displaying an image and black for each frame on the entire screen area of the liquid crystal display device and a technique of partitioning the screen area of the liquid crystal display device into, for example, two areas, and alternately displaying an image and black for each frame on one area while alternately displaying black and an image for each frame on the other area (see Jpn. Pat. Appln. KOKAI Publication No. 2001-42282).
As described above, however, since this technique displays one image by alternately performing image display and black display in two frames, the frame frequency needs to be doubled in order to perform display without causing flicker. However, the liquid crystal does not allow obtaining a sufficient response speed corresponding to the doubled frame frequency.